As a tenant - a student tenant, no less - your rights are virtually squat.
In practice the agent or landlord has a lot of leverage but you can often win if you use the law to your advantage. In particular there is a very specific set of steps they have to follow to evict you.
Even in housing association properties, you can have a 2 year "trial" period.
You only have to lightly scratch below the surface these days to find rights eroded left and right.
EDIT: I said "in place of ASTs", but ASTs aren't always appropriate.
This is mainly in the context of house/flat rentals though; I realise that perhaps per-room rentals may have special cases.
Might even recommend going to court over it.
